Food holding cabinets are used in restaurants and food services to maintain or regulate the temperature of a prepared food product until it is ready for sale or consumption. Some food holding cabinets use a thermocouple to sense the temperature of the cabinet interior or the temperature of a shelf or other interior surface. Other holding cabinets use a temperature-sensitive resistor to sense temperature within a food holding cabinet.
One problem with prior art temperature-sensitive resistances and thermocouples is that when they are used to measure temperature, the circuitry that measures a voltage or resistance requires calibration. Since each thermocouple and each temperature-sensitive resistor will have somewhat unique or different characteristics, circuitry that measures a voltage from a thermocouple or the resistance of a temperature-sensitive resistance needs to be calibrated to each device.
Those of ordinary skill in the electronic arts know that semiconductor P-N junctions have a well-known relationship between the junction voltage and the junction's temperature. A semiconductor can therefore be used to sense or measure temperature if it is properly coupled to interface circuitry. Since the relationship between junction voltage and junction temperature is well known, a semiconductor temperature sensor can avoid the need for calibration required by various prior art sensors.
Since most food holding cabinets (holding cabinets) keep food warm by heating a shelf or other surface in the holding cabinet, it is preferable for a semiconductor temperature sensor to be thermally coupled to the heated shelf or other surface. A method and apparatus for measuring temperature in a food holding cabinet using a semiconductor would be an improvement over the prior art.